1. Field of the Invention
The instant invention relates to microscopy in general, and to reflectance microscopy in particular. The instant invention also specifically deals with illumination of a specimen to be observed.
2. Description of the Prior Art
Conventional reflectance or dark field microscopy utilizes condensing lenses and vertical illuminators, which usually tend to make for very complex and expensive systems. The related U.S. Pat. No. 5,734,498 issued to the same inventors overcame the need for expensive lighting and complex systems of condensing lenses for transmission light microscopy by the use of a chromophoric illuminator placed near the specimen to be observed. The same principles disclosed in U.S. Pat. No. 5,734,498 are applied in the instant invention. Therefore, U.S. Pat. No. 5,734,498 is incorporated herein in its entirety by reference thereto. However, U.S. Pat. No. 5,734,498 falls short of a solution for reflectance microscopy because reflectance microscopy generally requires a light source on a same side as is the objective lens relative to a plane of the specimen normal to the optical path. Specifically, light is not passed through the specimen from a side thereof opposite to the objective lens. Rather the specimen is observed due to light reflected off the specimen and back into the objective lens.
Therefore, there is a need for an illuminator that does not obstruct the line of view between the objective lens and the specimen.
There is a need to provide an illuminator that does not require the complexity of a plurality of condensing lenses and expensive lighting, and yet provides high resolution of the specimen during observation.
There is a need to provide an illuminator that is capable of emitting light when stimulated by a common or readily available, inexpensive light.
There is also a need to provide a narrow range of emitted frequencies to reduce spectral impurities from the illuminator. Furthermore, there is a need to provide emitted light from the illuminator that is isotropic.
Another need is to provide emitted light that is generally isotropic, but which emanates with greater intensity from portions of the illuminator. In most cases, the illuminator needs to have good diffusion. However, there is also a need in some cases to be able to selectively provide emitted, diffused light at greater intensity in some regions of the illuminator.
The instant invention achieves all the needs set forth above and specifically does so in a way that enables reflectance microscopy. In order to fulfill the stated needs, an illuminator having special size and shape characteristics was sought.
In the preferred embodiment, the apertured illuminator is provided in the form of a toroid. Alternatively expressed, the illuminator is disk shaped with a cylindrical hole through the center of the disk. However, it is contemplated that the illuminator may be configured differently. For example, a U-shaped illuminator will also substantially surround a specimen and provide an aperture or opening through which viewing may occur. Alternatively, the illuminator may be provided in a plurality of pieces in order to occupy space on more than one side of the specimen and yet permit viewing through an opening between the pieces.
The illuminator of the instant invention is placed as close as possible to the specimen so that light emitted from the illuminator reaches the specimen and reflects off of the specimen with a sufficient intensity to reach the user""s eye or the recording medium in a camera. Another advantage of the instant advantage is that a failure to illuminate the specimen properly is devoid of the myriad of adjustment variables that plagued the prior art systems having multiple condensing lenses. In the instant invention, if the illuminator is properly stimulated and is sufficiently close to the specimen, the specimen will be isotropically illuminated.
To locate the illuminator as close as possible to the specimen and permit unobstructed viewing of the specimen, the aperture is centered on a main axis of the objective lens. The illuminator is positioned between the specimen and the objective lens so that the emitted light (i.e., light emitted from the illuminator), strikes the side of the specimen facing the objective lens. In this configuration, emitted light reflects off the specimen and enters the user""s eye or a camera via the objective lens.
The source of radiant energy or light may be located anywhere so long as radiant energy has a clear path from the source to the illuminator. The radiant energy may enter the illuminator through any of its surfaces so long as it has an angle of incidence within the critical angle for the material of the illuminator. Furthermore, shadowing by structural elements of the microscope such as the stage should be avoided as much as possible. Generally, the radiant energy or light source should be on the same side as is the objective lens relative to a plane of the specimen which plane is normal to the optical path. While the illuminator should be located on or in the nearest possible proximity to the specimen, the illuminator may be located on an opposite side of the stage from the specimen.
Radiant energy or light enters the illuminator and is diffused therein. The emitted light emanates from all of the surfaces of the illuminator. Generally, this emission is in a random and uniform manner. However, there are certain cases in which localized higher intensities of emissions are produced as set forth above.
While the apparatus and method has or will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 USC 112, are not to be construed as necessarily limited in any way by the construction of xe2x80x9cmeansxe2x80x9d or xe2x80x9cstepsxe2x80x9d limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 USC 112 are to be accorded full statutory equivalents under 35 USC 112. The invention can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals.